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Method for the termination of anionic polymerization by Lewis acid

a technology of anionic polymerization and lewis acid, which is applied in the field of anionic polymerization termination by lewis acid, can solve the problems of product color retention and aging stability loss, and the antioxidants used for such purposes are not stable under a basic condition, and achieve the effect of enhancing the stability of the resulting polymer

Inactive Publication Date: 2007-03-08
KOREA KUMHO PETROCHEMICAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0014] Therefore, an object of the present invention is to provide a method for terminating anionic polymerization by employing effective and environmentally friendly Lewis acid as a terminating agent in the preparation of conjugated diene copolymers via anionic polymerization to enhance the stability of the resulting polymers.

Problems solved by technology

However, most antioxidants used for such purposes are not stable under a basic condition.
Consequently, even if the antioxidant is included in the polymeric solution, the resulting product lacks in both color retention and aging stability.
U.S. Pat. No. 5,225,493 discloses that melt viscosity of polymeric products is changed after thermal treatment and further loss of clarity has also found as a result of increased haze.
Disadvantageously, however, when boric acid is employed as a terminating agent in the preparation of a block copolymer of a monovinylidene aromatic monomer and an alkadiene, the resulting product still possesses an undesirable change in melt viscosity upon thermal aging (U.S. Pat. No. 5,225,493).
However, since alcohols used as the terminating agent and sulfuric acid or phosphoric acid used as the neutralizing agent have poor compatibility with a non-polar solvent utilized as a polymeric solvent, there are several disadvantages that it has difficulty in terminating the reaction quantitatively, it may result in corrosion associated with excess use of a strong acid, and also have difficulty in controlling the acidity.
Such organic moieties can be recovered by carrying steam coagulation to remove a solvent and thus generate an offensive odor by being remained in the polymer or wastewater by being remaind in water.
According to this patent, although problem associated the reaction termination after anion polymerization is resolved by employing general alcohols, it still causes a problem that excess alcohol impurities are remained since alcohols are used in the form of alkali methoxide.
When such excess alcohols and metal oxides are remained in the reactor, they cause deactivation of living polymers in the following reaction so that it may be difficult to control molecular weight.
Further, when methanol is used as a terminating agent, most methanol is needed to be removed from a recycling solvent which causes the formation of wastewater.
When chlorine is used, although less coupled compound is formed, it causes corrosion of the reactor.
However, it still has problems associated with a coupled compound and requires use of a neutralizing agent, is also returned to its original compound during the recovering process of solvent while neutralization, which have to be removed during the reaction.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Termination of the Polymerization of Styrene-Butadiene Block Copolymer Using Triethyl Aluminum

[0033] A 2L reactor was charged with Argon gas. 900 g of cyclohexane, 0.2 ml of tetrahydrofuran, and 40 g of styrene were placed thereto. The reaction solution was heated to a temperature of 50° C. 2 mmol of n-butyl lithium(1.3M cyclohexane solution) of an initiator was added to the reaction solution. 10 min later after the temperature of the polymerization reached highest, 120 g of butadiene was added to the reaction solution. 5 min later after the temperature of the polymerization of butadiene reached highest, 2 mmol of triethyl aluminum was added to the reaction solution to remove reactive living polymers. Then an antioxidant was added. After the polymerization was completed, 5 g of styrene was additionally added to observe the degree of removing reactive living polymers. The solvent was removed by employing steam stripping from resulting polymer solution to obtain styrene-butadiene blo...

example 2

Termination of the Polymerization of Butadienes Using Triisobutyl Aluminum Hydride

[0034] A 2L reactor was charged with Argon gas. 900 g of cyclohexane, 0.2 ml of tetrahydrofuran, and 175 g of butadiene were placed thereto. The reaction solution was heated to a temperature of 50° C. 2 mmol of n-butyl lithium(1.3M cyclohexane solution) of an initiator was added to the reaction solution. 5 min later after the temperature of the polymerization reached highest, 2 mmol of trisobutyl aluminum hydride was added to the reaction solution to remove reactive living polymers. Then an antioxidant was added. After the polymerization was completed, 5 g of styrene was additionally added to observe the degree of removing reactive living polymers. The solvent was removed by employing steam stripping from the resulting polymer solution, roll milled and further dried to obtain polybutadiene.

example 3

Termination of the Polymerization of Butadiene Using Triethyl Borane

[0035] A 2L reactor was charged with Argon gas. 900 g of cyclohexane, 0.2 ml of tetrahydrofuran, and 175 g of butadiene were placed thereto. The reaction solution was heated to a temperature of 50° C. 2 mmol of n-butyl lithium(1.3M cyclohexane solution) of an initiator was added to the reaction solution. 5 min later after the temperature of the polymerization reached highest, 2 mmol of triethyl borane was added to the reaction solution to remove reactive living polymers. Then an antioxidant was added. After the polymerization was completed, 5 g of styrene was additionally added to observe the degree of removing reactive living polymers. The solvent was removed by employing steam stripping from the resulting polymer solution, roll milled and further dried to obtain polybutadiene.

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Abstract

The present invention relates to a method for the termination of anionic polymerization by Lewis acid, more particularly, a method for terminating anionic polymerization by employing Lewis acid as a terminating agent to terminate terminally reactive group in the preparation of conjugated diene polymers so that the reaction may be terminated effectively without further couplings, there is no color fading, and it does not require additional neutralization process and a controlling process of pH since any basic product, which reacts with an antioxidant, is not produced.

Description

FILED OF THE INVENTION [0001] The present invention relates to a method for the termination of anionic polymerization by Lewis acid, more particularly, a method for terminating anionic polymerization by employing Lewis acid as a terminating agent to terminate a terminally reactive end group in the preparation of conjugated diene polymers so that the reaction is terminated efficiently without further couplings, there is no discoloration, and it does not require additional processes of neutralization and pH adjustment because there is no basic product produced, which may react with an antioxidant. [0002] Generally, homopolymers prepared by polymerization of conjugated diene monomers such as butadiene and isoprene, styrene-conjugated diene copolymers prepared by copolymerization of styrenes and conjugated dienes, or block copolymers such as styrene-butadiene-styrene(SBS) block copolymer and styrene-isoprene-styrene(SIS) block copolymer prepared by block polymerization of blocks with an...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C08F4/46
CPCC08F2/42C08F36/04C08F297/04C08F297/044C08F2/38C08F2/44
Inventor KIM, SAM-MINKIM, YOUNG JINHWANG, JIN MAN
Owner KOREA KUMHO PETROCHEMICAL CO LTD